     (illegal-argument "Cannot store layout in :text format which does "
                       "not come from a concept lattice."))
   (let [nodes       (vec (keys (positions layout))),
-        node-number (comp inc (seq-positions nodes))]
+        node-number (comp inc (seq-positions nodes)),
+        annotation  (annotation layout)]
     (with-out-writer file
       ;; Node
       (doseq [n nodes]


(define-layout-input-format :text
  [file]
  (let [lines (partition-by #(second (re-matches #"^([^:]*): .*$" %))
                            (line-seq (reader file)))]
    (when-not (<= (count lines) 5)


(add-layout-input-format :simple
                         (fn [rdr]
                           (= "conexp-clj simple" (read-line))))

(define-layout-output-format :simple
  [layout file]
